1. Field of the Invention
This invention relates to an improved barrel-shaped insulation displacing contact (IDC) for making electrical contact to conducting wires.
2. Description of the Prior Art
Barrel-shaped insulation displacing contacts are already known and shown for example in U.S. Pat. No. 3,863,318, whereby such contacts procure a number of advantages with respect to other IDC designs such as ease of manufacturing, an improved ability to accommodate conductors of different sizes, and good mechanical and electrical properties. Additionally, barrel-shaped IDC's are well adapted to mass termination i.e. a plurality of conducting wires can be simultaneously connected to the plurality of barrel-shaped IDC's in a simple, reliable and cost-effective manner.
In order to further improve the reliability and the cost-effectiveness of barrel-shaped IDC contacts, it would be desirable to increase the flexibility of the contacting edges of the IDC slots, in particular to decrease degradation of the contact pressure between the conducting wire and edges of the IDC slots caused by stress relaxation. Stress relaxation is caused by creep which is a permanent material displacement, the rate of which is a function of the temperature and stress within the material. By increasing the flexibility of the IDC contacts, stress within the contact is reduced, therefore reducing stress relaxation. In order to reduce the manufacturing cost, it would also be desirable to provide good access, during the plating procedure, to the inside of the barrel contact as the plating procedure can then be accelerated. The functional contact surfaces of IDC's i.e. the contact edges, are commonly plated in order to reduce contact corrosion which increases the electrical resistance between the conducting wire and IDC terminal, whereby not only the actual contact edge must be plated but also the surrounding surfaces as the corrosion "overflows". The latter is also to ensure that a sufficient plating thickness is achieved, to avoid excessive porosity of the plating layer.